Use filename based unique document ID in URL and for RPC.

Use filename based unique document ID in URL and for RPC.

The document ID is the glom document name with spaces (' ') replaced
with pluses ('+') and without the .glom extension.

This change is mostly a string substitution of 'documentTitle' for
'documentID'. The only code change is the addition of a Documents DTO to get the
filename to document title mappings as indicated below.

* src/main/java/org/glom/web/client/OnlineGlomService.java:
* src/main/java/org/glom/web/client/OnlineGlomServiceAsync.java:
* src/main/java/org/glom/web/client/activity/DetailsActivity.java:
* src/main/java/org/glom/web/client/activity/DocumentSelectionActivity.java:
Use Documents DTO to create the document links in the document
selection view.
* src/main/java/org/glom/web/client/activity/ListActivity.java:
* src/main/java/org/glom/web/client/activity/TableSelectionActivity.java:
* src/main/java/org/glom/web/client/place/DetailsPlace.java:
* src/main/java/org/glom/web/client/place/HasSelectableTablePlace.java:
* src/main/java/org/glom/web/client/place/ListPlace.java:
* src/main/java/org/glom/web/client/ui/DocumentSelectionView.java:
* src/main/java/org/glom/web/client/ui/DocumentSelectionViewImpl.java:
* src/main/java/org/glom/web/client/ui/ListView.java:
* src/main/java/org/glom/web/client/ui/ListViewImpl.java:
* src/main/java/org/glom/web/client/ui/TableSelectionView.java:
* src/main/java/org/glom/web/client/ui/TableSelectionViewImpl.java:
* src/main/java/org/glom/web/server/Log.java:
* src/main/java/org/glom/web/server/OnlineGlomServiceImpl.java: Change
getDocumentTitles() to getDocuments() and return the Documents DTO.
* src/main/java/org/glom/web/shared/Documents.java: New DTO for
transferring the filename to document title mappings.